to give student basic knowledge about welding

8/8/2019 To Give Student Basic Knowledge About Welding

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Earth cable.

U se in case of an insulation failure in some appliance, this

wire connected to the metal body will provide a path for the

current to flow on the ground.

Electrode stick.

used to conduct current through a workpiece to fuse two pieces together.


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Face shield .

to protect the eyes from UV rays and to protect the face fromthe heat.

Chipper.

To remove the slag after welding.


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Leather gloves.

to protect the finger from the heat form from the process.

Leather apron.

To protect the body from the heat form from the process.


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Wire brush .

To clean the work piece.


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1.3 Safety precautions

There is safety precautions that we need to learn to make sure

the safety. We need to wear safety equipment before doing the

welding process. Here some precaution that need to give attension.

1 . Wear safety equipment to avoid injury.

2. Remove all flammable material from the project.

3. U se suitable electrode with suitable keep voltage.

4. Do not stick the electrode to the work piece because this will

damage the power supply.

5. Keep the suitable fire extinguisher nearby.

6. Do not inhale the gas produce from the process.


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1.4 Fundamentals of arc welding

Arc welding is one of processes for joining metals. By

applying constant heat, metal at the joint between two

parts is melted and caused to intermix - directly, or more

commonly, with an intermediate molten filler metal. Upon

cooling and solidification, a metallurgical bond is created.

Since the joining is an intermixture of metals, the final

weldment potentially has the same strength properties asthe metal of the parts. This is in sharp contrast to non-

fusion processes of joining in which the mechanical and

physical properties of the base materials cannot be

duplicated at the joint.

In arc welding, the intense heat

needed to melt metal is produced

by an electric arc. The arc is

formed between the actual work

and an electrode that is manually

or mechanically guided along the joint. The electrode can either be a rod with the purpose

of simply carrying the current between the tip and the

work. Or, it may be a specially prepared rod or wire that

Fig. 1 The basic arc-welding circuit


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not only conducts the current but also melts and supplies

filler metal to the joint. Most welding in the manufacture

of steel products uses the second type of electrode.


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1.5 Operation procedure

1 . Clean the surface of the work piece.

2. Position the plate close together with sufficient gap for welding.

3. Select the suitable electrode.

4. Adjust the electric current.

5. Scratch or knock the electrode into the metal surface. To strike thearc and do a tack weld to hold the join .

6. Weld along the join and fill the welding groove completely .

7. Switch off the welding.

8. Remove the slag from welding bead.


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1.6d Results and Observation.

Arc Welding

Some observation has made during the process. There is some problemhappend .

Observation from the angle

y 30

Molding size form from the welding is small. The molding is not perfect. It is hard to ensure the molding patern.

y 45

Molding size form from the welding is fine. The molding is perfect.Its easier to follow the molding patern.

y 90

Molding size form from the welding is big. The molding is not perfect. Its hard to follow the pattern because the hand will get tired.


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Observation from the speed

y Fast

The molding form is in small size .this is because the heat transfer is not long enough to make the work piece mold .

y Medium

The molding form is in perfect size. This is because the heattransfer is enough to make the work piece mold perfectly.

y Slow

The molding form is in large size. This because the heat transfer isto much and this make the work piece mold too much.

Observation from the distance between work piece and the arc rod.

y Cm

The welding is not happened. This is the distance is to far to makethe charge transfer.

y Cm

The welding is happened. Its easy to control.

y Cm


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A process for joining two pieces of metal in which the required high

temperature is obtained by the combustion of acetylene gas and oxygen.

The gases are thoroughly mixed in the nozzle or tip of the welding torch

to ensure perfect combustion. The weld may be formed directly betweentwo adjoining surfaces, but usually metal from a welding rod is fused in

between the surfaces of the joint.


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2.2 Tools and equipment

Oxygen and acetylene cylinder to keep the oxygen gas and acetylene gas.

High pressure blow pipe mixing the oxygen gas and acetylene .


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Gas welding hoses.

To transfer the gas from cylinder to the High pressure blow pipe.

Gas pressure regulator.

Indicates the pressure of the gas.


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Face shield .


Fire starter

give spark to start the welding.


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Leather gloves.

to protect the finger from the heat form from the process.

Leather apron.

To protect the body from the heat form from the process.


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Wire brush .


Filler rod To make the work piece connected .


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2.3 Safety precaution

There is safety precautions that we need to learn to make surethe safety. We need to wear safety equipment before doing the

welding process. Here some precaution that needs to give

attention.

1 . Wear proper protection.

2. Do not inhale the gases and the fumes.

3. Do not weld dirty or corrosion work piece.

4. Keep your head out from the fumes.

5. Wear clean fire resistance cloth.

6. Keep the suitable fire extinguisher nearby.7. Make sure oxygen gas in good quota .

8. Make sure there is no leaking at the hoses.


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Figure 2:

The GTAW process is versatile and can be used on ferrous and

nonferrous metals. An arc is produced between a nonconsumable

electrode and the work to be welded. The weld is shielded from the

atmosphere by a shielding gas that forms an envelope around the weld

area.


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2.5 Operation procedure

1 . Clean the surface of the work piece.2. Position the plate close together with sufficient gap for welding.

3. Adjust the gas pressure.

4. Open the acytelne nozzle . Start with the spark of fire.

5. Then open the oxygen gas.

6. Weld along the join by give heat to the filler wire and fill the

welding groove completely .

7. Switch off the oxygen gas then acytelena.

8. Remove the slag from welding bead.


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Results and Observation

Gas welding

Some observation has made during the process. There is some problemhappen.


y 30

Molding size form from the welding is small. The molding is not perfect. It is hard to ensure the molding patern. This because the heatis not enough to mold the work piece.

y 45

Molding size form from the welding is fine. The molding is perfect.Its easier to follow the molding patern.this is because heat is enough.

y 9 0

Molding size form from the welding is big. The molding is not perfect. Its hard to follow the pattern because the hand will get tired.This is because the heat go through over the limit for the work piece.


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y Fast

The molding form is in small size .this is because the heat transfer is not long enough to make the work piece mold .

y Medium

The molding form is in perfect size. This is because the heat

transfer is enough to make the work piece mold perfectly.

y Slow

The work piece leak. This because the heat transfer is to much andthis make the work piece mold too much.

Observation from the distance between work piece and heat.

y Cm

The work piece is hard to mold. This is the distance is to far tomake the heat transfer.

y Cm

The welding is happened. Its easy to control the molding.


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y Cm

The work piece easy to leak. Because the heat source is close. Heattransfer is over the limit for the work piece.


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Gas metal arc welding (GMAW), sometimes referred to by its

subtypes metal inert gas (MIG) welding or metal active gas (MAG)

welding, is a semi-automatic or automatic arc welding process in which

a continuous and consumable and wire electrode a shielding gas are fed

through a welding gun. A constant voltage, direct current power source

is most commonly used with GMAW, but constant current systems, as

well as Alternating current, can be used. There are four primary methods

of metal transfer in GMAW, called globular, short-circuiting, spray, and

pulsed-spray, each of which has distinct properties and correspondingadvantages and limitations.


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Air cooled welding torch

This where the wire goes out and it combined with coolent

gas.

Gas cylinder

U sed to store coolant gas such as inert gas


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Filler wire To give heat source to molt the work piece.

Face shield .



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Wire brush .



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3.3 safety precaution

There is safety precautions that we need to learn to make surethe safety. We need to wear safety equipment before doing the

welding process. Here some precaution that needs to give

attention.

1 . Spray the silencer with

2. Do not inhale the gas.

3. Wear safety equipment.

4. Make sure the gas is functioning.


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3.4 Fundamental of the process

MIG stands for metal inert gas . In stick welding the flux on the

electrode melts and forms a gas to shield the puddle from the

atmosphere. The atmosphere has hydrogen, nitrogen, oxygen, and other

gases that will cause weld defects if allowed to get into the weld pool.

In MIG, a spool of solid-steel wire is fed from the machine, through a

liner, then out of a contact tip in the MIG gun. The contact tip is hot , or electrically charged, when the trigger is pulled and melts the wire for the

weld puddle. This is accomplished in several ways. This article

discusses short-circuit welding.

In short-circuit welding, small droplets of molten wire, heated when

short-circuited, flow together to make a puddle as they touch the base

metal. Inert gas flows out of the gun and keeps the weld puddle shielded

from the atmosphere. Thus, metal inert gas . Inert means the gas will not

combine with another element; so inert gases, like helium and argon,

were used.


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3.5 Steps and procedure

1 . Clean the work piece .

2. Switch on the machine.

3. Then adjust the current supply to 1 20A ,make sure the protection

gas is exist.

4. Start the welding process by pushing the button at the nozzle.

5. Finish welding and turn off the machine.

6. Let the work piece cooled and clean it.


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3.6 Results and Observation

Gas shielded arc welding

Some observation has made during the process. There is some problem happen .


y 30The line that I made is not perfect. It is hard to control the welding.

y 45

The molding made is perfect. But it is not recommended.y 9 0The molding made is perfect .but is hard to see where the welding go.


y Fast

The molding form is in small size .this is because the heat transfer is not long enough tomake the work piece mold .

y Medium

The molding form is in perfect size. This is because the heat transfer is enough to makethe work piece mold perfectly.

y Slow

The work piece leak. This because the heat transfer is to much and this make the work piece mold too much.


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Observation from the distance between work piece and heat.

y Far from work piece

The welding does not happening because the wire dint touch the work piece.

y Medium rangeThe welding occur and its perfectly welded.

.

y Too closeIs hard because the nozzle should not touch the work piece.


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1.6 learning outcome of the practice

A rc welding From the practice that I has done, we need to welding by follow the

rule. We cannot let the electrode stick to the work piece because this will

damage the power supply.

While doing the welding we cannot make it to fast or to slow. This

will make the joining easy to break. We need to ensure that the welding

process is correct or else it would not join. The power supply is divide

into 2 section of power supply, alternate current and direct current.

Normally people use alternate current.

G as welding

When doing the gas welding we must not apply oxygen gas more then

acetylene gas because it will blow up. When welding do not apply to

much heat at one place for long period the work piece will broken.

When turn off the gas , close the oxygen hoses first then acetylene.


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1.7 conclusion of practice

From the practical I learned how to do the welding. I also learn that arcwelding is more often used daily, because its low cost. When doing the

welding process we need to do it with medium speed because its will not

get the perfect molding.

to give student basic knowledge about welding

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